同时伴有tel／abl融合基因和IgH／TCRr基因重排的儿童急性粒单核细胞白血病一例

t(9；12)(q34：p13)的白血病极其罕见．我们发现1例携带这种染色体易位的白血病患儿，并对tel/abl融合基因的表达和IgH/TCRr基因重排进行了研究。     

t(14;18)易位的分子基础和致病机理

t(14;18)(q32;q21)涉及14q32上的IgH基因和18q21上的bcl-2基因,易位结果形成bcl-2/IgH融合基因。bcl-2的断裂区在3′端的非翻译区内,该区对bcl-2的表达起调节作用。融合基因仍能编码完整的bcl-2蛋白,由于失去了3′端的调节,使bcl-2过度表达、细胞寿命延长、凋亡减少,起到癌基因作用。转染bcl-2/IgH的转基因鼠,淋巴瘤的发生率明显高于对照组。在bcl-2的断裂区和IgH的D区和J区均有chi样序列,在IgH发生重排时,DNA重组酶对chi样序列的误认可能是发生易位的原因。     

伴有t(3;5)(q25;q34)的骨髓增生异常综合征急性髓系白血病变患者的分子特征

目的研究t(3;5)(q25;q34)的分子特征。方法R显带染色体核型分析和染色体涂染分析确定t(3;5)(q25;q34)存在。RT-PCR法检测患者NPM-MLF1融合基因、MLF1基因表达。PCR联合序列分析检测NPM基因突变。实时定量RT-PCR(Real-time PCR)检测Evi-1,MDS1／Evi-1表达。免疫组化染色确定MLF1和NPM-MLF1蛋白细胞定位分布。Western blot法检测bcl-2蛋白表达。结果染色体核型分析和涂染分析均证实存在染色体t(3;5)(q25;q34),NPM-MLF1融合基因阳性,经诱导治疗获得完全缓解后转为阴性。患者白血病细胞仅表达MLF1基因非编码蛋白剪接体,不表达Evi-1基因,弱表达MDS1／Evi-1。无NPM基因突变,未检出bcl-2蛋白表达。MLF1蛋白定位于细胞质,而NPM-MLF1则主要定位于胞核。结论t(3;5)(q25;q34)是髓系肿瘤的一种少见的染色体易位,该染色体易位导致形成NPM-MLF1融合基因是其发病的分子学基础。     

Evi-1基因及产物致白血病的研究进展

在小鼠模型系统中,Evi-1基因是第一个被发现能导致髓系白血病的反转录病毒整合位点[1-2]。该基因定位于人类的3q26染色体。包括急性髓系白血病(acute myeloid leukemia,AML)、慢性髓系白血病、骨髓增生异常综合征(myelodysplastic syndrome,MDS)在内的髓细胞恶性肿瘤中[3],3q26染色体重排异常导致Evi-1基因激活。更为重要的是,无论3q26染色体是否存在重排,Evi-1基因高表达都是AML生存的独立负性预后指标。此外,急性淋巴细胞白血病(acute lymphoblastic leukemia,ALL)和慢性淋巴细胞白血病中也存     

外套细胞淋巴瘤及其他伴t(11;14)(q13;q32)易位的B细胞疾患的超微结构

近年来,依据形态学及免疫表型,能够对不同类型的B淋巴细胞增殖性疾患作出较准确的鉴定;但对于不典型病例,由于实验特征存在一定程度重叠,难以准确鉴别。而且,低到中度恶性的非霍奇金淋巴瘤(NHL)往往进展为白血病,细胞遗传学及分子生物学对这些情况的鉴别诊断有一定价值。象t(14;18)(q32;q21)易位在滤泡中心型细胞淋巴瘤(FCL)那样,t(11;14)(q13;q32)易位是弥散性小细胞NHL的较特异标志,如外套细胞淋巴瘤(MCL)及部分慢性淋巴细胞白血病(CLL)、前B淋巴细胞白血病(B-PLL)、伴毛细胞性脾淋巴瘤(SLVL)、淋巴浆细胞性淋巴瘤(LPL)等,其另一特征性遗传学异常:该易位断裂点将11q13染色体上的bcl-1位点与染色体14q32上的免疫球蛋白重链连接区拼接在一起,t(11;14)易位导致bcl-1的下调,以致细胞     

急性早幼粒细胞白血病的维甲酸受体基因

业已发现,几乎所有的急性早幼粒细胞白血病(APL)均有t(15;17)染色体易位,其特异性高于慢性粒细胞白血病中的Ph′染色体。新近已阐明,t(15;17)染色体易位是由15号染色体上的PML基因与17号染色体上的维甲酸受体α_1基因(RARA)之间的重排所致。临床上全反式维甲酸能使70～90%APL患者获得完全缓解,因此本病与t(15;17)染色体易位、PML—RARA基因重排之间的关系也受到了相应的重视。本文主要叙述由t(15;17)染色体易位引起的RARA基因重排以及PML—RARA融合基因在APL发生中的作用。     

AML1-ET09a异构体在伴有t(8;21)的M2型急性髓系白血病中临床意义的研究

t(8;21)(q22;q22)是急性髓系白血病中最常见的一种非随机染色体易位,约40%～50%的AML-M2(FAB分型)患者存在此种染色体易位[1].t(8;21)(q22;q22)形成AML1ETO融合基因,虽然AML1-ETO融合蛋白能够改变基因的表达及造血细胞的增殖,但它并不能直接导致白血病的发生[2].     

混合谱系白血病基因重排与急性白血病

涉及染色体11q23的异常是造血系统肿瘤的常见改变,该异常导致位于11q23处的混合谱系白血病(MLL)基因发生重排,与多种伙伴基因发生融合。MLL基因编码蛋白主要包括3个功能区域:转录抑制区、转录激活区和DNA结合区,它起着转录因子功能,在人体发育及细胞分化过程中,起着重要调控作用。MLL基因重排包括易位、部分串联重复、缺失、片段扩增等,MLL易位可产生许多不同类型的融合基因,最终诱导白血病发生。MLL重排的白血病有特异生物学特性,已成为白血病中的一个特殊亚型。     

AML1-ETO融合基因和白血病

许多急性髓系白血病(AML)是由于造血祖细胞染色体平衡易位而形成具有增殖优势的白血病细胞克隆,AML中最常见的t(8;21)(q222;q22)易位所涉及的野生型AML1、ETO基因对维持正常造血至关重要,而易位所产生的AML1-ETO融合基因则干扰正常造血细胞增殖与分化,并诱导白血病发生,同时也为诊断及治疗含有该融合基因的白血病提供了靶点.     

BCR/ABL阳性细胞对STI571耐药机制的研究进展

在慢性粒细胞白血病、成人急性淋巴细胞白血病以及儿童急性淋巴细胞白血病中常常发现染色体t(9;22)(q34;q11)易位。这种易位在22号染色体产生BCR/ABL融合基因,导致细胞恶性的扩增。ST1571(以前称谓CGP57148B)抑制Bcr/Abl酪氨酸激酶活性。然而人们在对BCR/ABL阳性细胞研究中发现了对STI571耐药的细胞株,目前的研究认为BCR/ABL基因的扩增与过度表达是对STI571耐药的主要机制。     

基因atm与慢性淋巴细胞白血病

共济失调毛细血管扩张突变基因（atm）为肿瘤抑制基因，位于人类染色体的11q22-23，主要参与DNA损伤识别和修复，并在DNA双链断裂诱导的信号级联转导通路中起到枢纽作用。慢性淋巴细胞白血病（CLL）可出现高频率的atm基因杂合性缺失和核苷酸突变，并与其发病及侵袭性病程有关。本文将对atm基因的特点、作用机制及其在慢性淋巴细胞白血病中作用的研究进展作一综述。     

基因atm与慢性淋巴细胞白血病

共济失调毛细血管扩张突变基因(atm)为肿瘤抑制基因,位于人类染色体的11q22-23,主要参与DNA损伤识别和修复,并在DNA双链断裂诱导的信号级联转导通路中起到枢纽作用。慢性淋巴细胞白血病(CLL)可出现高频率的atm基因杂合性缺失和核苷酸突变,并与其发病及侵袭性病程有关。本文将对atm基因的特点、作用机制及其在慢性淋巴细胞白血病中作用的研究进展作一综述。     

荧光原位杂交技术在慢性淋巴细胞白血病检测中的应用评估

本研究探讨与评估应用间期荧光原位杂交技术(FISH)检测慢性淋巴细胞白血病(CLL)遗传学异常的价值。应用间期FISH技术检测32例初诊CLL患者的del(13q14.3)、del(11q22.3)、del(17p13.1)、del(13q14)和12号染色体三体,同时对免疫表型不典型的10例初诊患者检测IGH/CCND1融合基因。结果表明,在32例病例组中FISH检测出26例(81.3%)基因异常,包括D13S25缺失14例,RB1缺失11例,12号染色体三体9例,P53缺失6例,ATM缺失4例;涉及1种基因异常的12例,其中12号染色体三体7例,D13S25缺失3例,P53缺失1例,ATM缺失1例;涉及2种基因异常的11例,其中D13S25/RB1缺失的7例,另4例均包含P53缺失;涉及3种以上基因异常的病例3例;10例免疫表型表达CD5+CD23-的初诊患者中2例IGH/CCND1(+)。结论:应用间期FISH技术检测CLL基因组的异常,可大大提高异常染色体的检出率,各基因异常有其不同的特点;IGH/CCND1融合基因的检测在CLL诊断中有重要意义。     

Preferential linkage of bcl-2 to immunoglobulin light chain gene in chronic lymphocytic leukemia

Most of human follicular lymphomas possess the t(14;18) chromosome translocation that juxtaposes the IgH gene to the 3' region of bcl-2 in a head-to-tail configuration. Here we show that the rearrangement of the bcl-2 gene occurs in a significant fraction (approximately of 10%) of B cell CLL. In all cases analyzed, breakpoints on chromosome 18 clustered at the 5' flanking region of the bcl-2 gene, and no rearrangements were found at the major or minor breakpoint clustering region (3' region of bcl-2 gene) typical of the t(14;18) chromosome translocation. All of the rearranged bcl-2 genes were juxtaposed with the Ig lambda or K genes in a head-to-head configuration. These results imply that the bcl-2 gene is preferentially linked to the IgL genes in CLL and could function in leukemogenesis.     

双色荧光原位杂交技术检测慢性淋巴细胞白血病IgH基因易位

目的 了解慢性淋巴细胞白血病（CLL）中染色体14q32上IgH基因易位情况，探讨其与CLL疾病进展的关系。方法 运用位于14q32上IgH基因两端的序列特异性DNA探针IGHC、IGHV和双色间期荧光原位杂交（FISH）技术对70例初发的B细胞CLL（B—CLL）患者的间期细胞进行IgH基因易位重排情况的检测。结果 70例B—CLL中8例（11．4％）有IgH基因易位重排，其阳性细胞率为10．5％～53．0％之间，且IgH基因易位在不同性别、年龄和Binet分期中差异无统计学意义（P〉0．05）。结论 IgH基因异位在B—CLL中属易发事件，对B—CLL的发生和发展的作用有待进一步研究。FISH是一种在分析B—CLL中IgH基因易位异常方面较为快速、准确和敏感的方法。     

间期荧光原位杂交技术检测慢性淋巴细胞白血病ATM基因缺失

目的探讨慢性淋巴细胞白血病(CLL)中ATM基因缺失及其与其他染色体异常及临床分期的相关性。方法运用间期荧光原位杂交技术(I-FISH)和Spectrum OrangeTM标记的位于11q22.3的序列特异性DNA探针ATM对50例初诊CLL患者的染色体标本进行了ATM缺失的检测,同时检测del(13q14)、del(17p13.1)和免疫球蛋白重链基因重排。临床分期按照Binet分期方法。结果50例患者中有6例(12%)ATM缺失;其中4例伴有其它染色体异常。20例Binet A期患者中,3例(15%)存在异常;10例Binet B期患者中,2例(20%)存在异常;13例Binet C期患者中,1例(7.7%)存在异常。ATM缺失在Binet A、B及C期中无统计学差异(P>0.05)。结论I-FISH与常规染色体分析技术相比是一种快速、准确及敏感的方法,对我国CLL患者的预后预测价值有待进一步的深入研究。     

Telomeric IGH losses detectable by fluorescence in situ hybridization in chronic lymphocytic leukemia reflect somatic VH recombination events

Routine interphase fluorescence in situ hybridization (FISH) analysis of chronic lymphocytic leukemia (CLL) with LSI IGH/CCND1 assay, applied to differentiate CLL from leukemic mantle cell lymphoma, identified a subset of cases (42/174) with translocation-like IGH signal pattern. To unravel the underlying 14q32/IGH aberrations, 14 of these cases were subjected to cytogenetic, detailed FISH, and V(H) mutation analyses. FISH identified cryptic losses of various portions of the IGHV region in all 14 cases. Fine mapping of these V(H) deletions revealed a strict correlation between their distal border and localization of the used VH gene, suggesting that they are not oncogenic but reflect physiological events accompanying somatic V-D-J assembly. This hypothesis was further supported by FISH analysis of 20 CLL and hairy cell leukemia cases with the known V(H) usage showing a constant loss of sequences proximal to the used gene, identification of V(H) deletions in normal B cells, and their exclusive demonstration in B cell malignancies, but not of T cell and myeloid linage. Given that these cryptic physiological VH losses in B cells may seriously complicate analysis of B cell leukemia/lymphoma and lead to false conclusions, FISH users should take them into consideration when interpreting IGH aberrations in these malignancies.     

Whole-genome scanning by array comparative genomic hybridization as a clinical tool for risk assessment in chronic lymphocytic leukemia

Array-based comparative genomic hybridization (array CGH) provides a powerful method for simultaneous genome-wide scanning and prognostic marker assessment in chronic lymphocytic leukemia (CLL). In the current study, commercially available bacterial artificial chromosome and oligonucleotide array CGH platforms were used to identify chromosomal alterations of prognostic significance in 174 CLL cases. Tumor genomes were initially analyzed by bacterial artificial chromosome array CGH followed by confirmation and breakpoint mapping using oligonucleotide arrays. Genomic changes involving loci currently interrogated by fluorescence in situ hybridization (FISH) panels were detected in 155 cases (89%) at expected frequencies: 13q14 loss (47%), trisomy 12 (13%), 11q loss (11%), 6q loss (7.5%), and 17p loss (4.6%). Genomic instability was the second most commonly identified alteration of prognostic significance with three or more alterations involving loci not interrogated by FISH panels identified in 37 CLL cases (21%). A subset of 48 CLL cases analyzed by six-probe FISH panels (288 total hybridizations) was concordant with array CGH results for 275 hybridizations (95.5%); 13 hybridizations (4.5%) were discordant because of clonal populations that comprised less than 30% of the sample. Array CGH is a powerful, cost-effective tool for genome-wide risk assessment in the clinical evaluation of CLL.     

Quantification of bcl-2/JH fusion sequences and a control gene by multiplex real-time PCR coupled with automated amplicon sizing by capillary electrophoresis

Follicular lymphoma is characterized by the presence of the t(14;18)(q32;q21) chromosomal translocation which juxtaposes the bcl-2 gene at 18q21 with the immunoglobulin heavy chain locus at 14q32. Quantification of t(14;18) carrying cells in FL patients can be achieved by real-time PCR, a highly sensitive technique for evaluating treatment efficacy and minimal residual disease. Despite the many advantages of real-time technology for this purpose, one disadvantage is that current real-time t(14;18) PCR assays amplify a control gene as a normalizer in a separate reaction. Since each PCR reaction has its own kinetics, separate PCR assays for target and control sequences can potentially result in inaccurate quantification of t(14;18)-positive cells. In addition, the real-time t(14;18) PCR assays do not determine the size of the amplified fusion sequence, which is helpful for excluding contamination and is commonly used to demonstrate clonal identity between pre- and post-treatment specimens from a patient. To address these limitations, we designed a multiplex real-time PCR protocol that allows amplification of control and target genes in the same reaction and precise size determination of bcl-2/JH fusion sequences by capillary electrophoresis. This multiplex PCR assay is equally sensitive to previous assays, allows more accurate quantification of bcl-2/JH fusion sequences, and is more convenient.     

应用荧光原位杂交技术检测慢性淋巴细胞白血病的基因组异常

目的 探讨应用组合荧光原位杂交(panel fluorescence in situ hybridization,panel FISH)技术对慢性淋巴细胞白血病(chronic lymphocytic leukaemia,CLL)基因组异常检测的价值.方法 分别应用序列探针D13S25(13q14.3)、RB1、p53、ATM(11q23)和着丝粒探针12号(CSP12)等5种荧光素标记的DNA探针,对17例CLL患者进行FISH检测,并和常规细胞遗传学检测结果进行比较.结果 17例CLL患者中,常规细胞遗传学检测出1例(1/17)有染色体异常,为49,XX,+3,+8,+18;组合FISH检测出10例(10/17)有染色体异常,包括D13S25缺失4例、ATM缺失2例、p53缺失1例、D13S25合并RB1同时缺失2例、多种异常1例.FISH检测的总检出率高于常规细胞遗传学检测.结论 组合FISH技术是检测CLL患者染色体基因组异常的有效手段,与常规细胞遗传学方法相结合则可明显提高CLL染色体异常的检出率.